CN1080376C - Fuel tank and general purpose engine provided with the same - Google Patents

Abstract

A fuel tank wherein upper and lower case members, which are flange-connected together, to improve the safety of an engine by preventing a fuel overflowing a fuel injection port in an upper wall of the fuel tank thereof from falling from the fuel tank onto a high-temperature cylinder portion and electrical parts, and so as to prevent the occurrence of vibration of the fuel tank and noise ascribed to such vibration. The upper case member has around the fuel injection port a substantially cross-sectionally trapezoidal, one-side opened, and the upper surface of the fuel tank is formed so as to descend from a central portion thereof in the outward direction toward the opened side of the recess. On both sides of the recess, grooves extending in the same direction as this recess are provided. The upper and lower case members are fused to each other at web portions of lip-carrying flanges.

Description

Oil tank and general engine having the same

The invention relates to an oil tank and a general engine with the same.

Fuel tanks for general-purpose small engines used in automobile engines and agricultural machinery are formed by forming the upper and lower tanks from metal plates by press forming, and joining them together with flanges.

This kind of automobile fuel tank is generally located under the bottom plate of the rear part of the car body, and there are rotating shafts such as propulsion shafts and control force transmission shafts passing through the fuel tank, so a concave portion transverse to the front and rear directions is provided on the fuel tank. Defects such as rust will occur if it remains in the concave portion.

The fuel tank shown in Fig. 5～Fig. 6 is in order to avoid producing this bad phenomenon, and the fuel tank for the automobile published in Japanese Patent No. 63-159324, Fig. 5 is a top view, and Fig. 6 is C-C of Fig. 5 Sectional view.

In Fig. 5～Fig. 6, 1 is fuel tank, 11 is the gear box that is equipped with the rear wheel control of this fuel tank 1 rear, 12, 13 is pinion shaft and rack bar, 14 is universal joint, 15 is Control force drive shaft.

A control force transmission shaft 15 , a universal joint 14 , and a pinion shaft 12 are disposed on the upper surface of the fuel tank 1 , and the fuel tank 1 is cross-cut by a recess 5 extending in the front-rear direction. Moreover, in order to ensure the capacity of the fuel tank, bulges 3, 3 bulge upward are formed at the rear left and right positions of the upper surface 2 of the fuel tank 2 divided by the concave portion 5, and at the same time, the surface of the fuel tank 1 is coated with an antirust layer. . Among the figure, 4 is an oil filling port, 31 is an oil pump installation surface, 32 is an instrument installation surface, and 41 is a ventilation pipe.

The shape of the bottom surface of the above-mentioned concave portion 5 is as shown in the side view Fig. 6, which is continuously formed into a convex shape with a long slope 6 forward downward and a short slope 7 backward downward, and is also coated with a resin coating. The apex portion 8 is located between the rear left and right bulging portions 3 , 3 . Therefore, even if water enters the recessed portion 5, the water will flow down along the forward and downward slope 6 and the rearward slope 7 of the bottom surface, and be discharged to the ground from the front and rear ends.

In addition, unlike the above-mentioned fuel tanks for automobiles, the fuel tanks of general-purpose small engines are generally provided with an oil filling port on the upper side of the fuel tank. This kind of oil tank is prone to the following problems, that is, oil spills from the oil injection port during oil filling, or the oil leaked from the oil supply nozzle flows along the surface of the oil tank. Contact with high-temperature oil cylinders will cause fires, and contact with electrical parts will cause parts Functional deterioration.

In order to prevent the occurrence of this undesirable phenomenon, a fuel tank for a general-purpose small engine can be provided, which has the following structure near the oil filling port, that is, through the inclined recess similar to Fig. 5 and Fig. The direction of the row to the ground structure.

This prior art fuel tank is illustrated by FIGS. 7 and 8 .

FIG. 7 is a front view of a general-purpose engine having the above-mentioned fuel tank, and FIG. 8 is a top view corresponding to FIG. 7 . In Fig. 7 and Fig. 8, 50 is an engine, 51 is an engine main body, 52 (refer to Fig. 8 ) is an output shaft, 53 is a muffler, 54 is an air filter, 55 is a carburetor, and 56 and 57 are throttle valves. 58 is a recoil starter (recoil starter), and 59 is a handle (grip) of the recoil starter 58. 61 is an oil tank, 60 is a cork connected to the oil tank 61, 62 is an instrument device, 63 is a mark, 64 is an oil filler cap, and the oil cylinder shaft (not shown) of the engine main body 51 is from the bottom of the muffler 53 to the output shaft. The direction of 52 is inclined.

The above-mentioned oil tank 61 is constructed in such a way that a thin copper plate is processed into two upper and lower pot-shaped boxes by pressure forming, and the flanges 61a provided on the outer peripheral part of the box are seam-welded, and the upper surface is approximately horizontal. A smooth slope with a slight downward slope is formed from the center to the periphery. In addition, around the oil filling port 61b (see FIG. 7 ) provided in the center, a conical surface 61c forms a concave portion, the bottom surface of the concave portion has an appropriate slope that decreases outside, and extends toward the direction of the recoil starter 58, forming a section facing downward. The trapezoidal recessed portion, namely, the trapezoidal recessed portion 61d has an opening on the side of the recoil starter 58 at the end. In this way, the fuel overflowing from the oil filling port can be guided to one side of the recoil starter 58 to be dropped and discharged.

Also, in FIGS. 7 to 8 , the left side of the fuel tank 61 is concentrated with high-temperature oil cylinders and electrical components, and oil must be prohibited from entering this area.

As shown in Figures 7 to 8, a general-purpose engine oil tank 61 forms a trapezoidal recess 61d around the oil filling port on the upper surface of the oil tank 61, and the bottom of the recess 61d is inclined to the side of the recoil starter 58. In the case of adopting this structure Next, when the oil overflows from the oil injection port or drips from the oil supply nozzle and leaks around the oil injection port, once it flows outside the trapezoidal recess 61d, it will flow laterally perpendicular to the trapezoidal recess 61d.

Also, even in the fuel tank 1 of an automobile engine shown in FIGS. 5 to 6 , when the oil flowing in the concave portion 5 flows to the outside, it flows laterally along the flange.

The oil flowing in the lateral direction will cause a fire if it comes into contact with a high-temperature oil cylinder, and if it comes into contact with electrical parts, it will reduce the function of the electrical parts or induce failure. In addition, in the above-mentioned fuel tank 61 or 1, since the upper and lower tanks are made of thin copper plates, it is easy to cause vibration and noise due to resonance with the vibration of the engine.

The first purpose of the present invention is, in view of the problems existing in the above-mentioned prior art, propose a kind of fuel tank, it can avoid overflowing from the oil filling port on the fuel tank, or the oil that leaks on the fuel tank when filling oil etc. drips from this fuel tank After falling, it contacts with the high-temperature cylinder part and electrical parts, improving the reliability of the engine.

A second object of the present invention is to provide an engine which prevents the vibration of the fuel tank and the resulting noise.

In order to solve this problem, the present invention proposes a fuel tank in which an upper case and a lower case are joined together by a flange, and an oil filling port is provided on the top of the upper case. This fuel tank is characterized in that,

On the upper surface of the upper case, there is a downward-sloping concave portion including the periphery of the above-mentioned oil filling port. In the water slide-shaped groove, at least the groove on the one-way side is divided into sections by ribs, and an open groove leading from the groove to the outside is provided in each section.

In this case, it is preferable to provide a plurality of arc-shaped grooves that are open in one direction at a portion other than the concave portion on the upper surface of the upper case.

The fuel tank described above is preferably applied to general purpose engines.

The present invention proposes a general-purpose engine. Its specific structure is that an oil tank is provided on the upper part of the engine. Composed, a recoil starter device is provided at the shaft end of the crankshaft. This general-purpose engine is characterized in that a recess is provided on the upper casing of the above-mentioned oil tank, and the recess includes the periphery of the oil filling port. All the recesses One side of the recoil starting device is open, and the outer side is in a downward slope shape. At the same time, a water slide-shaped groove is provided along the outer periphery of the above-mentioned flange part, and in the water slide-shaped groove, at least the recoil The groove on one side of the starting device is divided into sections by ribs, and an open groove leading from the groove to the outside is provided in each section.

In this case, a plurality of arc-shaped grooves can be provided on the upper part of the fuel tank other than the recess, and these grooves are open on the side of the recoil starter device.

According to this invention, when oil is injected into the oil tank, the oil leaked onto the oil tank mainly flows to the one-way side, that is, the concave portion where the recoil starter device is lowered, and then flows into the water slide-shaped groove, and flows from the groove to the bottom of the groove. The communicating open slots discharge to the outside.

In addition, the above-mentioned oil tank should be mounted on the engine main body of the general-purpose engine in such a way that the part of the water slide-shaped groove on the side of the recoil starter device is located at a lower position slightly lower than other parts.

This general-purpose engine, because one side of its output shaft is connected with generator, operating machine, and is provided with high-temperature muffler on the upper side of output shaft, therefore, when adopting this invention, the water-slider shape groove will be set like this, that is to say In order to make the side of the recoil starter device in a low temperature state below without the above-mentioned obstructing member, the oil dripping from the upper surface of the oil tank can be discharged to the side of the recoil starter device, which can improve safety.

The oil flowing in the direction perpendicular to the discharge direction (direction of the recoil starter) of the concave portion on the top of the tank flows into a plurality of arc-shaped grooves, and then flows from the grooves to the recoil starter. side, then flows into the water-slip-shaped groove, and finally discharges from the above-mentioned open groove to the outside.

Therefore, according to this invention, the oil leaked to the upper surface of the oil tank is collected in the water slide groove on the outer periphery of the flange part through the above-mentioned concave part and the arc-shaped groove, and is discharged from the open groove toward the low-temperature recoil starter. Therefore, Oil does not move laterally along the joint flanges of the upper case and the lower case, and does not come into contact with high-temperature oil cylinders or electrical parts, preventing flames or malfunctioning of electrical parts.

In addition, since the water-slider-shaped grooves are separated by ribs, even if a large amount of oil flows into the above-mentioned grooves, the ribs can be used to prevent the oil from moving in the circumferential direction of the flange of the grooves, so that the oil can be discharged from the open grooves without Overflow from the above-mentioned water slide-shaped groove, or flow in the circumferential direction.

In the present invention, the above-mentioned flange portion is composed of a notched flange formed along the entire circumference of the upper case and the lower case. body welded.

According to this invention, the notched flange can increase the circumferential rigidity of the oil tank, and the above-mentioned water slide groove can also function as an oil discharge passage.

The upper box body and the lower box body of the present invention can be made of resin materials.

Compared with the case of using sheet metal materials, the present invention can increase the thickness of the box body without increasing the weight, and the above-mentioned multiple arc-shaped grooves can improve the rigidity of the upper box body, and can also increase the strength at the same time, which can prevent vibration and noise from the fuel tank.

The present invention also proposes a fuel tank, wherein the planar shape of the upper tank and the lower tank are substantially square, and are joined at the flange, and an oil filling port is provided at the center of the upper tank.

The feature of this fuel tank is that the upper box body and the lower box body are made of resin material, and the upper box body is provided with a unidirectional side opening around the above-mentioned oil filling port and a trapezoidal cross-section. shaped concave portion, and a higher surface is formed on it, that is, it is lowered from the central portion to the outside of the one-way side at a certain slope. a groove open on the outer side of the aforementioned one-way side,

The above-mentioned upper case and lower case are welded at the connection plate portion of the notched flange formed along the entire periphery.

In this case, it is preferable to form a plurality of the grooves having arc-shaped cross-sections.

In addition, in the present invention, on the flange with the cutout of the upper box and the outer peripheral surface of the upper box, a water slide-shaped groove is formed along the entire circumference of the upper box. The side slots are divided into sections, and each section is provided with an open slot leading to the outside.

According to the present invention, when oil is injected into the fuel tank, the oil leaked onto the fuel tank mainly flows into the generally trapezoidal concave portion lowered on one side, and then flows into the water slide-shaped groove, and flows from the opening groove of the groove. discharged to the outside.

Also, the oil flowing from the top of the upper case to the direction substantially perpendicular to the discharge direction of the concave part flows into a plurality of arc-shaped grooves, and then the oil in the grooves flows to the above-mentioned one-way side, that is, the discharge side, and then It flows into the water slide-shaped groove, and flows from the above-mentioned open groove to the outside.

That is, according to the present invention, the oil that overflows or leaks onto the top of the upper casing of the oil tank flows from the recess as large as a trapezoid and the grooves formed on both sides of the recess on the top of the upper casing to form a circular cross-sectional shape or the like. The low-level side flow flows to the low-level side of the water slide-shaped groove provided on the notched flange, and is discharged from the open groove provided on the groove to the outside, so the oil does not move laterally along the flange and Contact with high temperature cylinders or electrical parts.

In addition, since the ribs are used to space the water-slider-shaped grooves, even if a large amount of oil flows into the grooves, the ribs prevent the oil from moving in the circumferential direction, and the oil is discharged from the open grooves so that the oil does not move in the circumferential direction.

And because the upper box body and the lower box body are made of resin material, compared with the sheet metal material box body, neither the weight nor the thickness can be increased, and the multiple sections formed on both sides of the above-mentioned trapezoidal concave part are arc-shaped Such grooves play a role in increasing the rigidity of the box, and at the same time can also improve the strength of the box and suppress vibration and noise.

A brief description of the accompanying drawings follows:

Fig. 1 is a top view of a fuel tank of a general-purpose engine according to an embodiment of the present invention (view along the direction A of Fig. 2 ).

Fig. 2 is a front view of the above fuel tank.

Fig. 3 is a view (side view) taken in the direction of B in Fig. 2 .

Fig. 4 is a partial frontal axonometric view of the above fuel tank.

Fig. 5 is a plan view showing an example of a conventional fuel tank for an automobile engine.

Fig. 6 is a cross-sectional view of line C-C in Fig. 5 .

Figure 7 is a front view of a conventional single cylinder engine with a prior art fuel tank.

Fig. 8 is a plan view of the above-mentioned prior art engine.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the dimensions, materials, shapes, and relative arrangement positions of components described in the embodiments are not limited to the scope of the present invention unless otherwise specified, and are merely illustrative examples.

Fig. 1 is a top view of a fuel tank of a general-purpose engine according to an embodiment of the present invention (view in the direction of A in Fig. 2), Fig. 2 is a front view of the above-mentioned fuel tank, and Fig. 3 is a side view of the above-mentioned fuel tank (view in the direction of B in Fig. 2) , Figure 4 is a partial top axonometric view of the above fuel tank.

Figures 7 to 8 of the present invention show an example of an improved fuel tank mainly used in general-purpose small engines, so the description of the following embodiments also uses Figures 7 to 8.

That is to say, the general-purpose small engine of the embodiment of the present invention has the same basic structure as that shown in Figs. 7 to 8 except for the oil tank.

In FIGS. 1 to 4 , 70 is an oil tank, and its structure is as follows.

71 to 72 are resin-molded upper and lower casings, 74 is a cap screwed into the outer periphery of an oil filling port 71b described later to cover the oil filling port, and 73 is a meter device.

The upper box body 71 is shown in Figure 2, and its plane shape is approximately square, and the top forms a protruding pot shape, and the central part and from the central part to the side of the recoil starter 58 (see Figures 7 to 8) (Figure 1 The outer circumference of the center Z arrow direction) forms a slope that descends to the outside according to an appropriate slope, and the other three directions (up, down, and left directions in Figure 1) roughly form a higher curved surface in the middle horizontally.

In addition, a trapezoidal concave portion 71c is formed in the central portion of the upper case 71. The trapezoidal concave portion is formed in such a way that the conical surface 71a around the oil filling port 71b described later is concave downward in cross section, and the concave portion is flushed back. A trapezoidal recess 71c extending from one side of the starter 58 (hereinafter referred to as the discharge side).

An oil filling port 71b is formed on the inside of the conical surface 71a of the trapezoidal recess 71c, and a cap 74 is screwed onto the outer peripheral thread of the oil filling port 71b.

The bottom surface of the trapezoidal recess 71c is provided such that, as shown in FIG.

In addition, on both sides of the oil filling port 71b on the top of the upper case 71, there are a plurality of circular arc-shaped grooves 71d with a downward cross-sectional shape (see FIG. 3 ). It extends from a position on the opposite side of the discharge side toward the discharge side (in the direction of the Z arrow), and the discharge-side end portion is opened on the outside. Moreover, the notched flange 71e is provided in the whole outer periphery of the upper case 71. As shown in FIG.

As shown in FIGS. 3 to 4 , the notched flange 71e of the upper case 71 is provided with a square groove 71f opened upward along the entire circumference. On the connecting plate 71i which is the outer edge of the square groove 71f, open grooves 71h are provided at predetermined intervals along the entire circumference of the connecting plate 71i, or at least along the discharge side (direction of the Z arrow), and the open grooves connect the square grooves to each other. The interior and exterior of 71f are connected.

In addition, the square groove 71f provided on the discharge side (Z arrow side) is separated by a plurality of ribs 71g provided between the side wall of the upper case 71 and the connecting plate 71i, and each interval is provided with the above-mentioned groove. The opening groove 71h serves as a discharge groove.

The lower box body 72 is a pot-shaped box body that is convex downward. In order to ensure the oil-holding capacity, as shown in FIG. There are an oil outlet 72a communicating with the oil cock 60 (see FIG. 7 ), and a plurality of (four in the figure) mounting brackets 72b.

In addition, the lower case 72 is provided with a notched flange 72c along the entire circumference of the upper edge. Furthermore, the connection plate 72d of the notched flange 72c and the connection plate 71i of the notched flange 71e of the above-mentioned box body 71 are combined and welded by vibration welding.

The fuel tank 70 constructed in this way is mounted on the engine 50 shown in FIGS. 7 to 8. When the engine 50 is placed horizontally as shown in FIG. That is, the above-mentioned discharge side (Z side in FIG. 1 ) is slightly lowered downward.

On this engine 50, when filling oil from the oil filling port 71b of the oil tank 70, once the oil overflows from the oil filling port 71b, the overflowed oil will drop into the trapezoidal recess 71c from the conical surface 71a around the oil filling port 71b, and along the The trapezoidal recess 71c flows to the discharge side (Z arrow side) into the square groove 71f, and then flows to the outside from the three open grooves 71h near the center. The plate 72d falls to the ground and is discharged.

In addition, the oil leaked to the outside of the above-mentioned conical surface 71a and trapezoidal recess 71c flows in all directions, but mainly flows to the discharge side (Z arrow side) with a steep gradient. Among them, the oil flowing in the direction perpendicular to the discharge side, after filling the arc groove 71d, changes direction and flows toward the discharge side (Z arrow side), flows into the square groove 71f on the discharge side, and then flows from the 5 near the center. The opening slot 71h is discharged to the outside.

Also, the oil that has not flowed into the above-mentioned arc groove 71d flows into the square groove 71f in three directions other than the discharge side along the surface of the oil tank 70, and then flows from the square groove to the discharge side, and flows from the discharge side. The corner open slots 71h (there are 2 open slots on this side) are discharged to the outside. Therefore, the oil that drips onto the oil tank 70 and flows along the surface mainly flows into the square groove 71f through the trapezoidal recess 71c, and the oil that flows laterally enters the square groove 71f through the arc groove 71d. In addition, the oil that does not flow into the circular arc groove 71d directly flows into the square groove 71f, passes through the square groove 71f, and flows from the open groove 71h on the discharge side to the connection plate of the notched flange 72c on the outer periphery of the lower case 72. 72d, and drop and discharge from the connecting plate 72d. This prevents the oil from flowing to the side of the hot engine parts and electrical parts.

In addition, when a large amount of oil flows into the square groove 71f on the discharge side, since the square groove 71f is partitioned by a plurality of ribs 71g, the oil does not flow in the circumferential direction in the groove 71f, but is discharged from the open groove 71h. to the outside.

Also, because the upper casing 71 and the lower casing 72 of the above-mentioned oil tank 70 are made of light-weight resin material, the plate thickness can be increased without increasing the weight, and the plurality of arc-shaped grooves 71d can improve the rigidity. The role of can increase strength, suppress vibration and noise.

The present invention is not limited to the general-purpose small engine oil tank of this embodiment, and can also be used as the engine of automobile engine, construction machinery and vehicle, etc., and the upper box body and the lower box body having the oil filling port are joined together by the flange part. All fuel tanks are applicable.

As described above, according to the present invention, the following effects can be obtained, that is, the oil leaked to the top of the oil tank is collected in the water-sliding groove on the outer periphery of the flange part through the concave part and the arc-shaped groove formed on the top of the upper tank, and then drained from the oil tank. The open slots are discharged toward the low-temperature recoil starter, so the oil will not move laterally along the joining flange of the upper case and the lower case to contact the high-temperature oil cylinder, nor will it contact electrical parts, which can prevent fires or malfunction of electrical parts.

In addition, especially by separating the water slide-shaped grooves with ribs, even if a large amount of oil flows into the grooves, the ribs can suppress the oil from moving in the circumferential direction of the flange, and the oil can be discharged from the open grooves without The oil overflows from the above-mentioned water chute-shaped groove or flows toward the circumference of the flange, so that the oil is surely discharged to the side of the recoil starter.

Also, according to the structure of the present invention, since the oil dripping from the fuel tank can be discharged to the side of the recoil starter which is low temperature and free from obstacles, safety can be improved.

According to the structure of the present invention, the notched flange can increase the rigidity in the direction of the periphery of the oil tank, and the above-mentioned water slide groove can function as an oil discharge passage.

According to the present invention, by using resin materials to form the upper and lower tanks of the fuel tank, compared with the fuel tank made of metal materials, the present invention can increase the thickness of the board without increasing the weight. The rigidity of the upper tank can be increased, and the strength can also be increased to obtain a high-strength fuel tank that prevents vibration and noise.

In addition, according to the present invention, the oil that overflows or leaks onto the upper casing of the oil tank flows in one direction, that is, to the lower position, in the substantially trapezoidal concave portion and the circular cross-section formed on both sides of the above concave portion on the upper casing. Side flow, flows to the lower side of the water-slider-shaped groove provided on the notched flange, and is discharged from the open groove provided on the groove to the outside, so the oil will not move laterally along the flange and come into contact with high temperature Cylinders or contact electrical parts.

Especially according to the present invention, since the above-mentioned water-slider-shaped grooves are separated by ribs, even if a large amount of oil flows into the grooves, the oil can be prevented from flowing in the circumferential direction by the ribs, and the oil can be discharged from the open grooves without Move around.

In this way, the oil that overflows or leaks to the oil tank, no matter how much or how little, is all collected to the low side and discharged to the outside without contacting the high temperature part and electrical parts, etc., so that fire and damage to the function of electrical parts can be reliably prevented. Bad things happen.

Also, since the upper case and the lower case are made of resin material, compared with the case made of sheet metal material, the plate thickness can be increased without increasing the weight, and the upper case formed on the upper case Multiple arc-shaped grooves can improve the rigidity of the box body, increase the strength of the box body, and suppress the generation of vibration and noise.

Claims (10)

1. An oil tank, which is formed by joining an upper case with an oil filling port and a lower case with a flange, It is characterized in that, on the upper surface of the upper box body, there is a concave part open on one side in one direction, including the periphery of the oil filling port, and the outer side is in a downward slope shape, and at the same time, a water tank is provided along the outer periphery of the flange part. A trough shaped like a water trough, in which at least the trough on the one-way side is partitioned into sections by ribs, and an open trough leading from the trough to the outside is provided in each section. 2 . The fuel tank according to claim 1 , wherein a plurality of arc-shaped grooves open to one side in one direction are provided on the upper surface of the upper tank other than the concave portion. 3 . 3. The fuel tank according to claim 1, wherein the flange portion is formed by a notched flange formed on the entire circumference of the upper case and the lower case, and the notched flange The connecting plate portion welds the upper box body and the lower box body together. 4. The fuel tank according to claim 1, wherein the upper case and the lower case are made of resin material. 5. An oil tank, wherein an upper case body and a lower case body respectively formed in a substantially square planar shape are joined together at a flange portion, and an oil filling port is provided on the upper center of the upper case body, It is characterized in that the fuel tank is constructed in such a way that the upper box body and the lower box body are made of resin material, and the upper box body has a slope-shaped concave portion open on one side, and the concave portion Including the periphery of the above-mentioned oil filling port, the cross-sectional shape is trapezoidal, and the top of the upper box body forms a middle higher surface that decreases from the central part to the outside of the one-way side according to a predetermined slope, and there are also two sides of the concave part. a groove extending in the same direction as the recess and opening on the one-way side, The upper case and the lower case are welded together at a connecting plate portion with a notched flange formed along the entire periphery. 6. The fuel tank according to claim 5, which is provided with a plurality of said grooves, the cross section of which is arc-shaped. 7. The fuel tank according to claim 5, wherein a water-slider-shaped groove involving the entire circumference of the upper casing is formed on the notched flange of the upper casing and the outer peripheral surface of the upper casing, and the water-sliding groove Among the grooves, at least the groove located on the one-way side is partitioned into sections by ribs, and an open groove leading to the outside is provided in each section. 8. A general-purpose engine, the upper part of the engine is equipped with a fuel tank, and the fuel tank is constructed in such a way that the upper case provided with the oil filling port and the lower case provided on the main body of the engine are joined together at the flange part. , the shaft end of the crankshaft of the general-purpose engine is provided with a recoil starter device, This general-purpose engine is characterized in that a recess is provided on the top of the upper casing of the above-mentioned oil tank, and the recess includes the periphery of the oil filling port. Also provided along the outer periphery of the above-mentioned flange portion is a water slide-shaped groove, and in the water slide-shaped groove, at least the groove on the side of the recoil starter device is spaced into sections with ribs, and each section has a An open slot leading from the slot to the outside is provided. 9. The general-purpose engine as claimed in claim 8, the upper casing of the fuel tank is provided with a plurality of arc-shaped grooves except the above-mentioned concave portion, and the recoil starting device of the arc-shaped groove is a The sides are open. 10. The general-purpose engine as claimed in claim 8, wherein the fuel tank is arranged on the main body of the engine, and when installed, the position on one side of the recoil starter device of the water slide-shaped groove is at a lower position than other positions. position.

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